1. Field of the Invention
The present disclosure relates generally to a transfer unit for transferring an image from an image carrying body and an image forming apparatus having the same, and more particularly, to a transfer unit of improved configuration of a transfer roller unit opposing an image carrying body with an intermediate transfer belt interposed therebetween and an image forming apparatus having the same.
2. Description of the Related Art
An image forming apparatus is an apparatus that forms a visible image with ink, or developer such as, for example, toner, on a printing medium, and may be designed for one or both of forming a color image by the use of multiple color ink or developer and forming a monochromatic, i.e., black and white, image using only the black ink or developer.
In such image forming apparatus, in order for color images, a number of developing cartridges corresponding to the number of different colors of the developer being used may be provided. Each developing cartridge may have an associated image carrying body on which a visible image of individual color is to be formed. The individual color images on the image carrying bodies are then transferred onto a transfer medium in cooperation with a transfer member such as transfer rollers that respectively oppose and press against the image carrying bodies in such a manner that the individual images overlap one over the other on the transfer medium to thereby form a full color image expressed as the overlapped combination of the individual color images.
When however a monochromatic image is formed, it is not necessary that all of the developing operate as only the developing cartridge corresponding to the black color developer is required to form the black image. Accordingly, It is also known in the art that, during a monochromatic image forming operation, the image carrying bodies corresponding to colors other than the black color are not operated, that those transfer rollers corresponding to the non-operating image carrying bodies may be separated away from the image carrying bodies to thereby minimize the wear and tear, and thus to prolong the life, of the image carrying bodies, and that such transfer rollers may be moved back into the position of pressing against the corresponding image carrying body as needed, i.e., when forming a color image.
When a transfer roller moves back into the pressing relation with an image carrying body as above described, due to the movement momentum of the transfer roller, the image carrying body may be subjected to an impact force. Over time, the repeated application of such force on an image carrying body may lead to a physical deformation such as abrasion, a crack, etc. in certain areas of the image carrying body, which may in turn lead to the deterioration of the image quality.